/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.hadoop.hbase.regionserver;

import java.io.IOException;
import java.util.List;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.CellComparator;
import org.apache.hadoop.hbase.HBaseInterfaceAudience;
import org.apache.hadoop.hbase.regionserver.compactions.CompactionContext;
import org.apache.hadoop.hbase.regionserver.compactions.DefaultCompactor;
import org.apache.hadoop.hbase.regionserver.compactions.ExploringCompactionPolicy;
import org.apache.hadoop.hbase.regionserver.compactions.RatioBasedCompactionPolicy;
import org.apache.hadoop.hbase.regionserver.throttle.ThroughputController;
import org.apache.hadoop.hbase.security.User;
import org.apache.hadoop.hbase.util.ReflectionUtils;
import org.apache.yetus.audience.InterfaceAudience;

/**
 * Default StoreEngine creates the default compactor, policy, and store file manager, or
 * their derivatives.
 */
@InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.CONFIG)
public class DefaultStoreEngine extends StoreEngine<DefaultStoreFlusher, RatioBasedCompactionPolicy, DefaultCompactor, DefaultStoreFileManager> {

    public static final String DEFAULT_STORE_FLUSHER_CLASS_KEY = "hbase.hstore.defaultengine.storeflusher.class";
    public static final String DEFAULT_COMPACTOR_CLASS_KEY = "hbase.hstore.defaultengine.compactor.class";
    public static final String DEFAULT_COMPACTION_POLICY_CLASS_KEY = "hbase.hstore.defaultengine.compactionpolicy.class";

    private static final Class<? extends DefaultStoreFlusher> DEFAULT_STORE_FLUSHER_CLASS = DefaultStoreFlusher.class;
    private static final Class<? extends DefaultCompactor> DEFAULT_COMPACTOR_CLASS = DefaultCompactor.class;
    private static final Class<? extends RatioBasedCompactionPolicy> DEFAULT_COMPACTION_POLICY_CLASS = ExploringCompactionPolicy.class;

    @Override
    public boolean needsCompaction(List<HStoreFile> filesCompacting) {
        return compactionPolicy.needsCompaction(this.storeFileManager.getStorefiles(), filesCompacting);
    }

    @Override
    protected void createComponents(Configuration conf, HStore store, CellComparator kvComparator) throws IOException {
        createCompactor(conf, store);
        createCompactionPolicy(conf, store);
        createStoreFlusher(conf, store);
        storeFileManager = new DefaultStoreFileManager(kvComparator, StoreFileComparators.SEQ_ID, conf, compactionPolicy.getConf());
    }

    protected void createCompactor(Configuration conf, HStore store) throws IOException {
        String className = conf.get(DEFAULT_COMPACTOR_CLASS_KEY, DEFAULT_COMPACTOR_CLASS.getName());
        try {
            compactor = ReflectionUtils
                    .instantiateWithCustomCtor(className, new Class[]{Configuration.class, HStore.class}, new Object[]{conf, store});
        } catch(Exception e) {
            throw new IOException("Unable to load configured compactor '" + className + "'", e);
        }
    }

    protected void createCompactionPolicy(Configuration conf, HStore store) throws IOException {
        String className = conf.get(DEFAULT_COMPACTION_POLICY_CLASS_KEY, DEFAULT_COMPACTION_POLICY_CLASS.getName());
        try {
            compactionPolicy = ReflectionUtils
                    .instantiateWithCustomCtor(className, new Class[]{Configuration.class, StoreConfigInformation.class}, new Object[]{conf, store});
        } catch(Exception e) {
            throw new IOException("Unable to load configured compaction policy '" + className + "'", e);
        }
    }

    /********
     * TODO_MA 马中华 https://blog.csdn.net/zhongqi2513
     *   注释：storeFlusher = DefaultStoreFlusher
     */
    protected void createStoreFlusher(Configuration conf, HStore store) throws IOException {
        String className = conf.get(DEFAULT_STORE_FLUSHER_CLASS_KEY, DEFAULT_STORE_FLUSHER_CLASS.getName());
        try {
            storeFlusher = ReflectionUtils
                    .instantiateWithCustomCtor(className, new Class[]{Configuration.class, HStore.class}, new Object[]{conf, store});
        } catch(Exception e) {
            throw new IOException("Unable to load configured store flusher '" + className + "'", e);
        }
    }

    @Override
    public CompactionContext createCompaction() {
        return new DefaultCompactionContext();
    }

    private class DefaultCompactionContext extends CompactionContext {
        @Override
        public boolean select(List<HStoreFile> filesCompacting, boolean isUserCompaction, boolean mayUseOffPeak,
                boolean forceMajor) throws IOException {

            /********
             * TODO_MA 马中华 https://blog.csdn.net/zhongqi2513
             *   注释：
             */
            request = compactionPolicy
                    .selectCompaction(storeFileManager.getStorefiles(), filesCompacting, isUserCompaction, mayUseOffPeak, forceMajor);
            return request != null;
        }

        @Override
        public List<Path> compact(ThroughputController throughputController, User user) throws IOException {
            return compactor.compact(request, throughputController, user);
        }

        @Override
        public List<HStoreFile> preSelect(List<HStoreFile> filesCompacting) {
            return compactionPolicy.preSelectCompactionForCoprocessor(storeFileManager.getStorefiles(), filesCompacting);
        }
    }

}
